A dam is a large wall built across a river to change the natural flow of water and make a deep lake form behind the wall. The water from dams is often used to water farm or supply water to a city, or to make electricity.
Damage is some kind of harm that is caused to something else, which doesn't completely break or destroy it but does reduce its usefulness or value. The tomato in the picture has been damaged by birds.
Damask is a pattern used on a variety of fabrics like silk and wallpaper. Damask patterns can come in a lot of different designs, but the most common is a damask rose pattern like the one in the picture.
Something is damp if it is slightly wet. The rocks around the waterfall are damp, and moss is growing on them.
Dampen is another word for suppress. Acoustic insulation like in the picture will dampen sound. Being given some bad news may dampen your spirits and put you in a bad mood.
Dancing is a way of moving that is usually set to music and is pleasant to watch. There are many different kinds of dance, from very formal dances like ballet that have defined movements, tribal and traditional dances from many cultures, through to unstructured dancing that young people do at nightclubs.
A dancer is a person who dances. Some people are employed as dancers, which makes them professionals. The woman in the picture is a ballet dancer.
Scientific name: taraxacum officinale
Dandelions are a small plant with yellow flowers. Most people consider them to be weeds. The seeds of the dandelion are spread by the wind, so they are light and fluffy. Some people say if you can blow all the dandelion seeds off at once, you are granted a wish.
Dandruff is when your head under your hair loses little white flakes of skin and they get caught in your hair or fall onto your shoulders. Dandruff can be itchy like in the picture, or just not be nice to look at. You can buy special shampoo to get rid of dandruff.